Aug. 23, 2010 -- Drinking water before each meal has been shown to help promote weight loss, according to a new study.

Brenda Davy, PhD, an associate professor of nutrition at Virginia Tech and senior author of a new study, says that drinking just two 8-ounce glasses of water before meals helps people melt pounds away.

The study is being presented at the 2010 National Meeting of the American Chemical Society in Boston.

"We are presenting results of the first randomized controlled intervention trial demonstrating that increased water consumption is an effective weight loss strategy," Davy says in a news release. "We found in earlier studies that middle aged and older people who drank two cups of water right before eating a meal ate between 75 and 90 fewer calories during the meal."

She tells WebMD that many people substitute sweet-tasting calorie-containing beverages for water.

"If you look at research on beverage consumption trends, our average intake of sugar-sweetened beverages has increased dramatically in the past three or four decades," Davy tells WebMD in an email. "So, likely we are drinking other beverages in place of water."

Drinking Water and Weight Loss

Her study included 48 adults between age 55 and 75 who were divided into two groups.

One group drank two cups of water before meals and the other didn't. All participants ate a low-calorie diet throughout the study.

After 12 weeks, water drinkers lost about 15.5 pounds, compared to non-water-drinking dieters, who lost only 11 pounds.

Davy tells WebMD that the study participants drank about 1.5 cups of water per day prior to joining in the study.

Not only were those who drank water before meals more successful after 12 weeks, but they also kept "the weight off for a full year after the weight loss study."

Even better, most water drinkers, followed for an additional 12 months, not only kept weight off but "even lost another 1 to 2 pounds," she tells WebMD.

The message, she says, is clear: "People should drink more water and less sugary, high-calorie drinks."

How Water Aids Weight Loss

She points out that folklore and everyday experience both have suggested that water promotes weight loss, but little scientific information has been offered on the topic.

This doesn't mean that good old H2O is a magic potion, but that drinking water may help people shed pounds for the simple reason that it has no calories and fills up the stomach, making people less hungry.

Davy says water makes people feel fuller, inducing them to eat less food. She also offers good news for those who prefer diet sodas and other drinks with artificial sweeteners, saying such liquid refreshment fills people up, too. But she advises against drinking beverages made tasty with sugar and high fructose corn syrup, which are high in calories.

Davy says no one knows how much water people should drink daily, and that the federal Institute of Medicine says healthy people can let thirst be their guide.

However, she recommends that women drink about nine cups of fluids every day, including water and other beverages, and men about 13 cups.

It is possible, she adds, to drink too much water, which can lead to a rare but serious condition known as water intoxication.

The study was funded by the Institute for Public Health and Water Research, a nonprofit, independent science and education organization.

This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.

SOURCES: News release, American Chemical Society.

2010 National Meeting of the American Chemical Society, Boston, Aug. 22-26, 2010.